The invention relates to an installation for separating or purifying gases, in particular a PSA, TSA or VSA unit, comprising at least one plane structure formed from a matrix supporting one or more phase change materials (PCM) and its use for gas separation or purification.
PSA or VSA units are suitable for separating gases by pressure cycling of the gas to be treated through an adsorbent bed (zeolite, activated carbon, etc.).
Adsorption is an exothermic mechanism. In fact, the thermal effects resulting from the enthalpy of adsorption have two consequences on the temperature in the bed, that is a stabilization, in steady state conditions, of an average temperature profile, with a cold point at the inlet; and a propagation, for each cycle, of an adsorption heat wave limiting the adsorption and a desorption cold wave limiting the desorption.
In present day separation units, the average temperature profile is optimized. The limiting thermal effect is the local cycling of temperature fluctuations, as recalled by document EP 1 888 470.
One solution consists in adding a phase change material (PCM) to the bed. In this way, at least part of the heat of adsorption and of desorption is absorbed by the PCM in the form of latent heat. However, the sprinkling of PCM powder on the agglomerated beads raises mixing problems, as stated by document U.S. Pat. No. 4,971,605.
Moreover, in this case, the material is subjected to the gas stream and may therefore gradually leave the system.
As regards this limitation, encapsulation of the PCM in microspheres of about a few microns in diameter offers the possibility of a shaping in a support matrix.
One problem that nevertheless arises is the shape of this matrix and its uniform incorporation in an adsorbent, catalyst or similar bed, which can be used in a PSA, TSA, VSA type of installation, a catalytic reactor or similar.
One solution of the invention is accordingly an installation for separating or purifying gases comprising at least one gas treatment vessel, characterized in that the said vessel comprises at least one plane structure comprising a matrix and at least one phase change material (PCM).
Depending on each case, the installation of the invention may comprise one or more of the following features:                the plane structure has a sheet or plate shape, preferably rigid,        the plane structure is formed essentially of one or more PCM,        the plane structure has a thickness of between 0.1 mm and 40 mm,        the matrix is made from fabric, metal or polymer,        the PCM(s) is(are) deposited, retained or impregnated on the matrix,        the said at least one gas treatment vessel comprises a plurality of plane structures,        the vessel is an adsorber or a catalytic reactor comprising a plurality of plane structures spaced from one another by inter-spaces, each inter-space comprising at least one adsorbent material or at least one catalyst material, preferably an adsorbent or catalyst material in the form of particles,        the adsorber or the reactor has a cylindrical or conical shape and the said plane structures are arranged radially in the adsorber or the reactor, preferably the adsorber comprises a central axial passage,        the said structures are arranged in one or more modules, the said modules being arranged in at least one adsorber or at least one catalytic reactor.        
The invention also relates to a method for separating or purifying gases, in which:                a) a gas to be treated is introduced into an installation according to the invention; and        b) a gas product is recovered at the outlet of the said installation.        
Preferably, a PSA, VSA or TSA type of adsorption process is used.
The gas to be treated is air, an H2/CO mixture, a synthesis gas, or a waste combustion gas.
The gas product is a gas selected from N2, O2, H2, CO2, argon and Co.